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DVW15 Sound Transmission in a Vacuum

Objective:

– To show that sound waves require a medium for transmission.

Apparatus:

  • Bell jar with speaker and microphone
  • Power Supply AC/DC
  • Vacuum plate
  • Vacuum pump
  • Audio generator (optional)
  • Audio amplifier (optional)
  • Speaker
  • Leads

DVW15 - Sound Transmission in Vacuum

Method:

As the Bell jar is evacuated, the amplified sound dies away rapidly to nil.

If the air is then re-admitted slowly, the sound gradually returns, to its original level.

Note:

Use a frequency of about 700 Hz, due to transducer behaviour. Also, use fairly high gain setting on amplifier, and a low gain setting on signal generator.

 

Bell jar experiment – sound needs medium for propagation – Video Created at the Rajesh Physics Center.

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